This page explains the configuration on TP-Link wireless access points managed by EAP controller for external Captive  Portal and RADIUS server authentication.

Sign-in to the EAP controller. In Wireless Settings click on the Edit button next to the SSID you wish to use for Captive Portal - tplink eap cp in our example.

Change Security Mode to None and enable Portal.

Click on Wireless Control -> Portal and change Authentication Type to External Radius Server and add server details. Change External Web Portal URL to the Splash page URL from the IronWifi console

Click on Free Authentication Policy and enter IronWifi web server IP address - / 32